ALLOWANCE FOR LOAN AND LEASE LOSSES - Changes in Allowance for Loan and Lease Losses (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2016		Sep. 30, 2015	Sep. 30, 2016		Sep. 30, 2015	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	$ 234,454		$ 221,518	$ 240,710		$ 222,395
Charge-offs	(46,566)		(26,067)	(101,467)		(151,028)
Recoveries	4,679		2,339	11,285		19,187
Provision For Loan Lease And Other Losses	21,503		31,176	63,542		138,412
Ending balance	214,070		228,966	214,070		228,966
Balance at end of period	72,682		51,859	72,682		51,859
Allowance for loan losses Purchased Credit Impaired	6,857		3,163	6,857		3,163
Ending balance: general allowance	134,531		173,944	134,531		173,944
Ending balance	8,863,654		9,140,462	8,863,654		9,140,462
Ending balance: impaired loans	912,854		842,713	912,854		842,713	$ 953,774	$ 806,509	$ 824,816	$ 945,407
Ending balance: purchased credit-impaired loans	168,141		176,085	168,141		176,085
Ending balance: loans with general allowance	7,782,659		8,121,664	7,782,659		8,121,664
Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	6,857	[1]	3,163	6,857	[1]	3,163
Residential Mortgage [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	38,955		33,783	39,570		27,301
Charge-offs	(8,514)		(5,094)	(27,352)		(13,815)
Recoveries	972		214	2,159		584
Provision For Loan Lease And Other Losses	4,553		6,958	21,589		21,791
Ending balance	35,966		35,861	35,966		35,861
Balance at end of period	9,667		18,705	9,667		18,705
Ending balance: general allowance	19,661		14,095	19,661		14,095
Ending balance	3,299,942		3,330,089	3,299,942		3,330,089
Ending balance: impaired loans	444,039		459,311	444,039		459,311
Ending balance: purchased credit-impaired loans	165,014		172,927	165,014		172,927
Ending balance: loans with general allowance	2,690,889		2,697,851	2,690,889		2,697,851
Residential Mortgage [Member] | Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	6,638	[1]	3,061	6,638	[1]	3,061
Commercial Mortgage [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	69,799		49,092	68,211		50,894
Charge-offs	(13,730)		(3,677)	(15,742)		(54,115)
Recoveries	335		20	414		6,515
Provision For Loan Lease And Other Losses	(152)		6,668	3,369		48,809
Ending balance	56,252		52,103	56,252		52,103
Balance at end of period	25,907		4,886	25,907		4,886
Ending balance: general allowance	30,126		47,115	30,126		47,115
Ending balance	1,545,014		1,562,538	1,545,014		1,562,538
Ending balance: impaired loans	198,500		104,046	198,500		104,046
Ending balance: purchased credit-impaired loans	3,127		3,158	3,127		3,158
Ending balance: loans with general allowance	1,343,387		1,455,334	1,343,387		1,455,334
Commercial Mortgage [Member] | Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	219	[1]	102	219	[1]	102
Commercial And Industrial Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	69,789		63,900	68,768		63,721
Charge-offs	(10,587)		(1,267)	(16,260)		(30,090)
Recoveries	929		327	1,885		3,386
Provision For Loan Lease And Other Losses	5,597		3,807	11,335		29,750
Ending balance	65,728		66,767	65,728		66,767
Balance at end of period	28,668		17,540	28,668		17,540
Ending balance: general allowance	37,060		49,227	37,060		49,227
Ending balance	2,167,011		2,222,324	2,167,011		2,222,324
Ending balance: impaired loans	178,174		174,983	178,174		174,983
Ending balance: purchased credit-impaired loans	0		0	0		0
Ending balance: loans with general allowance	1,988,837		2,047,341	1,988,837		2,047,341
Commercial And Industrial Loans [Member] | Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	0	[1]	0	0	[1]	0
Construction Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	2,747		11,865	3,519		12,822
Charge-offs	(19)		(103)	(623)		(4,787)
Recoveries	140		176	301		2,379
Provision For Loan Lease And Other Losses	2,480		(139)	2,151		1,385
Ending balance	5,348		11,799	5,348		11,799
Balance at end of period	3,004		2,128	3,004		2,128
Ending balance: general allowance	2,344		9,671	2,344		9,671
Ending balance	124,298		163,956	124,298		163,956
Ending balance: impaired loans	47,707		66,123	47,707		66,123
Ending balance: purchased credit-impaired loans	0		0	0		0
Ending balance: loans with general allowance	76,591		97,833	76,591		97,833
Construction Loans [Member] | Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	0	[1]	0	0	[1]	0
Consumer Loan [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	53,164		62,878	60,642		67,657
Charge-offs	(13,716)		(15,926)	(41,490)		(48,221)
Recoveries	2,303		1,602	6,526		6,323
Provision For Loan Lease And Other Losses	9,025		13,882	25,098		36,677
Ending balance	50,776		62,436	50,776		62,436
Balance at end of period	5,436		8,600	5,436		8,600
Ending balance: general allowance	45,340		53,836	45,340		53,836
Ending balance	1,727,389		1,861,555	1,727,389		1,861,555
Ending balance: impaired loans	44,434		38,250	44,434		38,250
Ending balance: purchased credit-impaired loans	0		0	0		0
Ending balance: loans with general allowance	1,682,955		1,823,305	1,682,955		1,823,305
Consumer Loan [Member] | Purchased Credit Impaired [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses Purchased Credit Impaired	$ 0	[1]	$ 0	$ 0	[1]	$ 0

[1] Refer to Note 6 - Loans Held for Investment -PCI loans for a detail of changes in the allowance for loan losses related to PCI loans.